rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BABAR_2011_I892421

Decay angles in $D_{s1}(2536)^+\to D^{*+}K^0$
Experiment: BABAR (PEP-II)
Inspire ID: 892421
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D83 (2011) 072003
Beams: e- e+
Beam energies: (5.3, 5.3) GeV
Run details:
  • e+e- to hadrons

Measurement of decay angles in the decay $D_{s1}(2536)^+\to D^{*+}K^0$ by BaBar.

Source code: BABAR_2011_I892421.cc
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief D_s1 decay angles
  class BABAR_2011_I892421 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(BABAR_2011_I892421);


    /// @name Analysis methods
    ///@{

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(), "UFS");
      // book histos
      book(_h_cP,1,1,1);
      book(_h_c ,2,1,1);
    }

    bool isK0(int id) {
      return id==310 || id==130 || abs(id)==311;
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const int DsID = 10433;
      const UnstableParticles& ufs = apply<UnstableFinalState>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::abspid==DsID)) {
	// decay angle
	int sign = p.pid()/DsID;
	Particle Dstar;
	if(p.children().size()!=2) continue;
	if(p.children()[0].pid()==sign*413 &&
	   isK0(p.children()[1].pid())) {
	  Dstar = p.children()[0];
	}
	else if(p.children()[1].pid()==sign*413 &&
		isK0(p.children()[0].pid())) {
	  Dstar = p.children()[1];
	}
	else {
	  continue;
	}
	// first boost to the D_s1 rest frame
	LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
	FourMomentum pDstar = boost1.transform(Dstar.momentum());
	double cTheta = pDstar.p3().unit().dot(p.momentum().p3().unit());
	_h_c->fill(cTheta);
	if(Dstar.children().size()!=2) continue;
	Particle D0;
	if(Dstar.children()[0].pid()== sign*211 && 
	   Dstar.children()[1].pid()== sign*421) {
	  D0 = Dstar.children()[1];
	}
	else if(Dstar.children()[1].pid()== sign*211 && 
		Dstar.children()[0].pid()== sign*421) {
	  D0 = Dstar.children()[0];
	}
	else
	  continue;
	// boost to D_s frame
	FourMomentum pD  = boost1.transform(D0.momentum());
	// to D* rest frame
	LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
	Vector3 axis = pDstar.p3().unit();
	FourMomentum pp = boost2.transform(pD);
	// calculate angle
	double cThetap = pp.p3().unit().dot(axis);
	_h_cP->fill(cThetap);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_cP);
      normalize(_h_c );
    }

    ///@}


    /// @name Histograms
    ///@{
    Histo1DPtr _h_cP,_h_c;
    ///@}


  };


  DECLARE_RIVET_PLUGIN(BABAR_2011_I892421);

}